Moderate exercise might help older adults’ blood vessels relax, a study has found - pointing to one reason why exercise lowers the risk of heart attacks and strokes.

As people age, their blood vessels can become more constricted and less pliable in response to blood flow, a change that contributes to high blood pressure and clogged arteries.

But in the new study, older men who took up regular exercise were able to substantially reduce this effect of aging.

The findings are good news for sedentary older adults, researchers say, because the benefit required only moderate activity - namely, taking a walk five times a week.

“This is exercise that I would stress can be done by most older adults,” said senior study author Dr. Christopher A. DeSouza of the University of Colorado in Boulder.

He and his colleagues report the findings in the medical journal Hypertension.

The study included 28 healthy but sedentary men: 13 in their 20s and 15 in their 60s. For the first phase of the research, DeSouza and his colleagues used a test called plethysmography to measure blood vessel function in each man’s forearm. They found that the older men’s blood vessels were generally more constricted than those of their younger counterparts.

Next, the researchers had eight of the older men begin a three-month exercise program, while the rest remained sedentary. The exercisers worked out moderately, typically walking for about an hour, five days per week.

At the end of the three months, the exercise group showed a sharp turnaround in blood vessel constriction - with test results looking more like those of the younger men from the earlier study than the sedentary group their own age.

The improvement in blood vessel function occurred without improvements in the men’s weight, body fat, blood pressure or other traditional indicators of heart health.

This is important, DeSouza told Reuters Health, because even if people aren’t seeing obvious benefits from exercise - like a smaller waistline - they may still be making improvements on the inside.

Another key point, he noted, is that all of the older men in the study had been long-time couch potatoes, yet were still able to benefit from starting an exercise routine in their 60s.

“It’s that old adage, ‘It’s never too late to start,” DeSouza said.

SOURCE: Hypertension, August 2007.